Techniques for adaptive LDPC decoding

Patent metadata

Field	Value
Publication number	US-9866241-B2
Application number	US-201615073034-A
Country	US
Kind code	B2
Filing date	Mar 17, 2016
Priority date	Sep 25, 2015
Publication date	Jan 9, 2018
Grant date	Jan 9, 2018

Abstract

Techniques are described for an adaptive low density parity check (LDPC) decoder. The techniques include receiving a first set of values corresponding to a first low density parity check codeword and noise, performing a first plurality of iterations of an iterative decoding algorithm using a first set of decoding parameters to decode the received first set of values, comparing a metric with a first threshold, and upon determining that the metric is larger than the threshold: selecting a second set of decoding parameters for the iterative LDPC decoder and performing a second plurality of iterations of the iterative LDPC decoding algorithm using the second set of decoding parameters to decode the received first set of values and generate a first set of decoded bits.

First claim

What is claimed is:

1. A method for adaptive decoding performed by a system that comprises a low density parity check (LDPC) decoder, the method comprising:
receiving a first set of values corresponding to a first LDPC codeword and noise;
performing a first plurality of iterations of an iterative decoding algorithm using a first set of decoding parameters to decode the received first set of values;
comparing a checksum value with a first threshold, wherein the checksum value corresponds to a number of parity check failures after the first plurality of iterations, and wherein the first threshold is defined based on at least one of: an error floor or a speed of the iterative decoding algorithm; and
based on the comparing:
selecting a second set of decoding parameters for the iterative decoding algorithm; and
performing a second plurality of iterations of the iterative LDPC decoding algorithm using the second set of decoding parameters to decode the received first set of values and generate a first set of decoded bits.

2. The method of claim 1 , wherein the second set of decoding parameters comprises one or more scaling factors and one or more initial log likelihood ratio (LLR) values.

3. The method of claim 1 , wherein at least one of the scaling factors in the second set of decoding parameters is different from a corresponding scaling factor in the first set of decoding parameters.

4. The method of claim 1 , wherein at least one of the initial log likelihood ratio (LLR) values is in the second set of decoding parameters is different from a corresponding LLR value in the first set of decoding parameters.

5. The method of claim 1 , wherein the number of parity check failures is associated with a decoded codeword after the first plurality of iterations.

6. The method of claim 1 , further comprising:
calculating the checksum value after each of the first plurality of iterations to generate a plurality of checksum values;
checking if a total number of the plurality of checksum values remain between the first threshold and a second threshold;
performing, based on the total number remaining between the first threshold and the second threshold, the second plurality of iterations of the iterative LDPC decoding algorithm using the second set of decoding parameters to decode the received first set of values and generate a first set of decoded bits.

7. The method of claim 1 , wherein the iterative decoding algorithm is a hard decoding message passing algorithm.

8. The method of claim 1 , wherein the first set of decoding parameters and the second set of decoding parameters are stored in a table comprising a plurality of sets of decoding parameters.

9. The method of claim 1 , wherein the LDPC codeword is irregular having at least a first column weight and a second column weight, wherein a first scaling factor corresponds to one or more columns having the first column weight and the second scaling factor corresponds to one or more columns having the second column weight.

10. An apparatus for adaptive decoding, comprising:
at least one processor configured to:
receive a first set of values corresponding to a first low density parity check (LDPC) codeword and noise;
perform a first plurality of iterations of an iterative decoding algorithm using a first set of decoding parameters to decode the received first set of values;
compare a checksum value with a first threshold, wherein the checksum value corresponds to a number of parity check failures after the first plurality of iterations, and wherein the first threshold is defined based on at least one of: an error floor or a speed of the iterative decoding algorithm; and
based on the compare:
select a second set of decoding parameters for the iterative decoding algorithm;
perform a second plurality of iterations of the iterative LDPC decoding algorithm using the second set of decoding parameters to decode the received first set of values and generate a first set of decoded bits; and

a memory coupled to the at least one processor.

11. The apparatus of claim 10 , wherein the second set of decoding parameters comprises one or more scaling factors and one or more initial log likelihood ratio (LLR) values.

12. The apparatus of claim 10 , wherein at least one of the scaling factors in the second set of decoding parameters is different from a corresponding scaling factor in the first set of decoding parameters.

13. The apparatus of claim 10 , wherein at least one of the initial log likelihood ratio (LLR) values is in the second set of decoding parameters is different from a corresponding LLR value in the first set of decoding parameters.

14. The apparatus of claim 10 , wherein the number of parity check failures is associated with a decoded codeword after the first plurality of iterations.

15. The apparatus of claim 10 , wherein the at least one processor is further configured to:
calculate the checksum value after each of the first plurality of iterations to generate a plurality of checksum values;
check if a total number of the plurality of checksum values remain between the first threshold and a second threshold;
perform, based on the total number remaining between the first threshold and the second threshold, the second plurality of iterations of the iterative LDPC decoding algorithm using the second set of decoding parameters to decode the received first set of values and generate a first set of decoded bits.

16. The apparatus of claim 10 , wherein the iterative decoding algorithm is a hard decoding message passing algorithm.

17. The apparatus of claim 10 , wherein the first set of decoding parameters and the second set of decoding parameters are stored in a table comprising a plurality of sets of decoding parameters.

18. The apparatus of claim 10 , wherein the LDPC codeword is irregular having at least a first column weight and a second column weight, wherein a first scaling factor corresponds to one or more columns having the first column weight and the second scaling factor corresponds to one or more columns having the second column weight.

19. A non-transitory processor-readable medium for adaptive decoding, comprising processor-readable instructions configured to cause one or more processors to:
receive a first set of values corresponding to a first low density parity check (LDPC) codeword and noise;
perform a first plurality of iterations of an iterative decoding algorithm using a first set of decoding parameters to decode the received first set of values;
compare a checksum value with a first threshold, wherein the checksum value corresponds to a number of parity check failures after the first plurality of iterations, and wherein the first threshold is defined based on at least one of: an error floor or a speed of the iterative decoding algorithm; and
based on the compare:
select a second set of decoding parameters for the iterative decoding algorithm; and
perform a second plurality of iterations of the iterative LDPC decoding algorithm using the second set of decoding parameters to decode the received first set of values and generate a first set of decoded bits.

20. The processor-readable medium of claim 19 , wherein the second set of decoding parameters comprises one or more scaling factors and one or more initial log likelihood ratio (LLR) values.

Assignees

• Sk Hynix Inc

Inventors

• Yen Johnson
• Prabhakar Abhiram
• Wang Chung-Li

Classifications

• H03M13/45

  Soft decoding, i.e. using symbol reliability information (H03M13/41 takes precedence) · CPC title

• H03M13/1177

  Regular LDPC codes with parity-check matrices wherein all rows and columns have the same row weight and column weight, respectively · CPC title

• H03M13/1111

  Soft-decision decoding, e.g. by means of message passing or belief propagation algorithms · CPC title

• H03M13/1128 Primary

  Judging correct decoding and iterative stopping criteria other than syndrome check and upper limit for decoding iterations · CPC title

• H03M13/658

  Scaling by multiplication or division · CPC title